Adhesive blend of polyolefins and grafted block copolymer of polystyrene

Abstract

Composition comprising a mixture of from about 30% to about 99.9% of a polyolefin base resin; from about 0.1% to about 50% of a graft polymerized block copolymer having polystyrene end blocks and an aliphatic middle block; from 0 to about 40% by weight of an elastomer different from the above components; and from 0 to about 30% by weight of a nonelastomeric second polyolefin made from different monomers from those of the polyolefin base resin. The composition can be used as an adhesive film or tie layer, optinally by coextrusion between layers to be joined. Coatings and coated substrates are also disclosed.

We claim: 
     
       1. An adhesive composition consisting of a mixture of: A. from about 30% to about 99.9% by weight of a polyolefin base resin selected from the group consisting of polypropylene; polyethylene; and compolymers of ethylene with vinyl acetate, vinyl alcohol, methyl acrylate, methylmethacrylate, ethyl acrylate, and ethyl methacrylate;   B. from about 0.1% to about 50% by weight of a graft polymerized block copolymer having polystyrene end blocks and at least one polymer of an olefin, diolefin, or mixture thereof or a hydrogenated polymer thereof as a middle block, graft polymerized by treatment with at least one monomer selected from carboxylic acids, their anhydrides, and mixtures thereof;   C. from 0 to about 30% by weight of a nonelastomeric second polyolefin made from different monomers from those of said polyolefin base resin; and   optional fillers, adhesion promoters and antioxidants.   
     
     
       2. The composition of claim 1, wherein said base resin consists essentially of polypropylene. 
     
     
       3. The composition of claim 1, containing from about 70% to about 98% by weight of said base resin. 
     
     
       4. The composition of claim 1, wherein the middle block of said graft polymerized block copolymer consists essentially of hydrogenated polybutadiene. 
     
     
       5. The composition of claim 1, wherein said graft-polymerized block copolymer is an ABA block copolymer having about 28% by weight polystyrene end blocks and 70% by weight of a middle block consisting essentially of hydrogenated polybutadiene, grafted with about 2% by weight maleic anhydride. 
     
     
       6. The composition of claim 1, wherein said monomer is maleic anhydride. 
     
     
       7. The composition of claim 1, containing from about 2% to about 30% by weight of said graft-polymerized block copolymer. 
     
     
       8. The composition of claim 1, containing from about 70% to about 98% by weight said base resin. 
     
     
       9. The composition of claim 1, wherein said base resin consists essentially of polypropylene and said nonelastomeric second polyolefin consists essentially of polyethylene. 
     
     
       10. The composition of claim 1, containing from about 10% to about 20% by weight of said nonelastomeric second polyolefin. 
     
     
       11. The composition of claim 1, wherein said base resin consists essentially of a copolymer of ethylene and vinyl acetate. 
     
     
       12. The composition of claim 1, wherein said base resin consists essentially of a copolymer of ethylene and methyl acrylate. 
     
     
       13. The composition of claim 1, wherein said base resin consists essentially of a copolymer of ethylene and ethyl acrylate. 
     
     
       14. The composition of claim 10, wherein said base resin consists essentially of polypropylene and said nonelastomeric second polyolefin consists essentially of polyethylene.